Intestinal flora is not an intermediate in the phylloquinone-menaquinone-4 conversion in the rat.
To elucidate the role of intestinal bacteria in the conversion of phylloquinone into menaquinone-4 (MK-4) we investigated the tissue distribution of vitamin K in germ-free rats. The rats were made vitamin K deficient by feeding a vitamin K-free diet for 13 days. In a subsequent period of 6 days, phylloquinone and menadione were supplied via the drinking water in concentrations of 10 and 50 micromol l(-1). Menadione supplementation led to high levels of tissue MK-4, particularly in extrahepatic tissues like pancreas, aorta, fat and brain. Liver and serum were low in MK-4. Phylloquinone supplementation resulted in higher phylloquinone levels in all tissues when compared with vitamin K-deficient values. The main target organs were liver, heart and fat. Remarkably, tissue MK-4 levels were also higher after the phylloquinone supplementation. The MK-4 tissue distribution pattern after phylloquinone intake was comparable with that found after menadione intake. Our results demonstrate that the conversion of phylloquinone into MK-4 in extrahepatic tissues may occur in the absence of an intestinal bacterial population and is tissue specific. A specific function for extrahepatic MK-4 or a reason for this biochemical conversion of phylloquinone into MK-4 remains unclear thus far.
Ronden
J E
JE
Department of Biochemistry, Cardiovascular Research Institute Maastricht, Maastricht University, The Netherlands.
Drittij-Reijnders
M J
MJ
Vermeer
C
C
Thijssen
H H
HH
D000818:Animals; D004032:Diet; D005856:Germ-Free Life; D007422:Intestines / Q000382:microbiology*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D014812:Vitamin K / Q000031:analogs & derivatives* / Q000032:analysis* / Q000096:biosynthesis / Q000378:metabolism; D010837:Vitamin K 1 / Q000032:analysis / Q000378:metabolism*; D024482:Vitamin K 2 / Q000031:analogs & derivatives; D014813:Vitamin K Deficiency
D024482:Vitamin K 2; D014812:Vitamin K; C030814:menatetrenone; D010837:Vitamin K 1